Prosthetic heart valves can replace defective human valves in patients. Prosthetic valves commonly include sewing rings, suture cuffs, or rings that are attached to and extend around the outer circumference of the prosthetic valve orifice. Because of their circular cross-sections, sewing rings that are implanted may not optimally fit the biological annulus into which a valve may be implanted. As a result, natural blood hemodynamics through and around the valve may be impaired, resulting in cloning, possible emboli production, and eventual calcification of the valve structure.
As patients grow, particularly pediatric patients, the leaflets of a valve may no longer be property sized to fit the annulus. Leaflets may also calcify or otherwise foul and need to be replaced. To replace the leaflets on a single-piece prosthetic valve, the entire valve must be removed, which may cause trauma to the annulus and jeopardize implantation of a replacement valve. Further, it may be difficult to work around and through leaflets of a valve to attach a leaflet-laden valve, possibly damaging the leaflets and extending the length of the valve replacement procedure.
Sewing rings can also be tedious and time consuming to secure to a valve orifice. To assemble multiple component heart valves, one component has to be sewn into another in vivo, resulting in a complex and time consuming process. The complexity of the procedure also provides a greater opportunity for mistakes and requires a patient to be on cardiopulmonary bypass for a lengthy period.
Multiple piece heart valves also typically require a significant amount of handling during implantation, potentially exposing the delicate leaflets to damage before or during in vivo implantation. Additionally, orientation of the components of a multiple piece heart valve is generally not defined by the device, making the implantation of the second piece of the valve less intuitive. The surgeon must align the components of the valve during in vivo assembly when limited access can impair dexterity and the fragile valve components are at risk of being damaged. Also, known multiple piece valves lack sufficient mechanical safeguards to insure that the surgeon will properly orient or secure the valve components. Once implanted, multiple component heart valves can have problems with the components fitting each other in a secure and stable manner. Improper fit can cause mechanical stress and hemodynamic anomalies leading to clotting, dislodgement or valve failure.
Accordingly, heart valves, particularly multiple piece valves that may be reliably implanted into biological heart annuluses, e.g., to maximize hemodynamic flow and/or ease implantation, would be useful.